Two sections are considered separately
The section between Mettlen and Hellbühl (Littau) is considered separately. It was upgraded to 380 kV in 1990, but is currently operating at just 220 kV. The Innertkirchen – Mettlen and Bickigen – Mettlen lines approach one another to the west of Rothenburg, from where they are bundled in the section to Mettlen. With this in mind, it makes sense to consider both lines together in this section in order to provide permanent relief for the settlement area. Swissgrid will therefore review the line routing in this area as part of the planned Bickigen – Mettlen line renovation. The line lead-in for the Innertkirchen substation will be considered separately within the Innertkirchen – Mettlen sectoral plan process: two additional transmission lines run parallel to the Innertkirchen – Mettlen line along a roughly two-kilometre section. As all three lines pass through the settlement area, the only option in this section is to install an underground cable.
The next stage of the sectoral plan process is for Swissgrid to devise suggestions for corridors within the specified planning territory. After that, a monitoring group appointed by the SFOE will come together with the federal authorities, the affected cantons and environmental associations to discuss and assess the planning corridor variants developed by Swissgrid. The monitoring group’s recommendation then continues on to the public collaboration stage. The Federal Council is expected to define the planning corridor with a specific transmission technology (overhead line, underground cable or a combined solution) between Innertkirchen and Mettlen in autumn 2025. Ideally, the renewal of the Innertkirchen – Mettlen extra-high-voltage grid will be completed by 2035. After that, the existing line, parts of which run through the settlement area, will be removed.